Inter alia U.S. Pat. No. 3,901,304 discloses a special truck to be used when exchanging pattern boards in an automatic apparatus for producing casting moulds as disclosed in U.S. Pat. No. 3,008,199. This apparatus has vertical joints between flaskless mould parts. Each mould part is produced successively by compaction of sand or the like between a pair of pattern boards supported by opposed pressing plates in a pressing chamber. After a mould part has been pressed the rear pressing plate and pattern board are moved so that a further movement of the front pressing plate and pattern board causes the mould to be transferred to a casting bed or conveyor and run up to its predecessor to form a casting cavity at the joint of both mould parts.
The truck referred to comprises at least one pair of transversely displaceable pattern board carriers that can be aligned with their respective pressing plate to which the pattern boards are locked in their position of use. After said locks have been released, the pattern boards can be manually pulled onto the carriers of the truck and brought to stock, from where another pair of pattern boards can be brought into the exchange position in relation to the pressing plates and transferred thereto and locked thereon.
To accelerate the exchange the truck may include two pairs of pattern board carriers, namely one pair for receiving the pattern boards hitherto used, and another pair for delivering another set of pattern boards, but even in this case a certain loss in production must be accounted for, because the exchange normally takes at least 3 minutes and frequently 6 to 8 minutes. Moreover, the changing operation requires a not quite ignorable manual work.
These circumstances are tolerated when casting in long series is concerned which only requires a few pattern board exchanges a day, but in order to reduce storage capacity and to allow quicker intervening in case casting errors are found, far more frequent exchanges are often desired, for instance up to 10 exchanges an hour, and such a desire cannot be complied with in an economically proper manner by use of the above mentioned truck.
Against this background it is a purpose of the invention to provide a plant which renders it possible to effect the pattern board exchange in a fraction of the time needed so far and with a minimum of manual work.